Reuseable snore/air flow sensor

ABSTRACT

A sensor for use with a polysomnograph in a sleep lab setting is made reusable by laminating a PVDF film and associated lead contacts within a flexible, moisture-impervious plastic envelope that is hermetically sealed about its periphery. Lead terminals within the envelope are adhered to the metalized surfaces of the PVDP film using a conductive adhesive which inhibits dislodgement of the leads from the sensor even with rough handling and cleaning.

CROSS-REFERENCE TO RELATED APPLICATIONS

This application claims priority to Provisional Application Ser. No.60/700,365, filed Jul. 18, 2005, the contents of which are herebyincorporated by reference.

BACKGROUND OF THE INVENTION

1. Field of the Invention

This invention relates generally to apparatus for monitoring respiratoryactivity, which also can include snoring activity, and more particularlyto a reusable pyro/piezo transducer for producing an electrical signalproportional to respiratory airflow and/or vibration due to snoringepisodes for subjects undergoing sleep studies.

2. Discussion of the Prior Art

Applicant's assignee, Dymedix Corporation of Minneapolis, Minnesota, haspioneered the development of improved sensors that are adapted to beattached to the upper lip or throat area of a patient that, duringsleep, produces an electrical signal proportional to inspiratory andexpiratory airflow and to episodes of snoring. In U.S. Pat. No.5,311,875, applicant first disclosed such a sensor embodying apolyvinylidene fluoride (PVDF) film as the active element of such arespiration activity sensor. The film has both pyroelectric andpiezoelectric properties and, as such, is responsive to both temperaturechanges and physical vibration, producing an electrical signal outputthat can be signal processed to effectively separate the temperaturechange induced signal from the signal due to vibration.

Improvements in the sensor are the subject of U.S. Pat. Nos. 6,894,427,6,551,256, 6,485,432, 6,491,642 and 6,254,545, the teachings of whichare hereby incorporated by reference as if set forth in full herein.

For the most part, the sensor construction described in theaforereferenced patents were intended for single-use application in thatthey would not hold up to repeated cleaning. More particularly, moisturecould permeate the layered construction to compromise the electricalinterface between the PVDF film and its connection to an electricallead. Moreover, the handling during cleaning operations would lead todetachment of the lead's contact with the PVDF film.

It is accordingly a principal object of the present invention to providea respiratory activity sensor especially constructed so as to bereusable. More particularly, the sensor or transducer of the presentinvention is designed to be moisture impervious and constructed suchthat lead wire pull-out is no longer a problem.

SUMMARY OF THE INVENTION

In fabricating the sensor of the present invention, a sandwichedconstruction is employed in which a PVDF film is coated on its opposedmajor surfaces with a conductive layer and a pair of lead wires having ametal tab attached to the distal ends thereof are positioned on oppositesides of the PVDF film using a carbon-laced adhesive as a conductivebonding agent between the lead wire's metal tabs and the conductivecoating on the PVDF film.

The PVDF film with the lead contact tabs affixed to its opposed majorsurfaces are sandwiched between upper and lower layers of double-sidedadhesive tape that adhere to the film layer, to a portion of the leadsand to one another. Next, a polyurethane film layer is adhered to theexposed sides of the double-sided tape. The polyurethane layers extendbeyond the perimeter edges of the double-sided tape and the edgeportions of the polyurethane layers are heat sealed to one another tototally encapsulate the PVDF film, the lead tabs and the layers ofdouble-sided adhesive tape in a moisture-proof manner.

DESCRIPTION OF THE DRAWINGS

FIG. 1 is an exploded view of the reusable sensor constructed inaccordance with a first embodiment of the invention;

FIG. 2 is an expanded edge view of the embodiment of FIG. 1; and

FIG. 3 is an exploded view of an alternative embodiment of a snoresensing element made in accordance with the present invention.

DESCRIPTION OF THE PREFERRED EMBODIMENT

Certain terminology will be used in the following description forconvenience in reference only and will not be limiting. The words“upwardly”, “downwardly”, “rightwardly” and “leftwardly” will refer todirections in the drawings to which reference is made. The words“inwardly” and “outwardly” will refer to directions toward and awayfrom, respectively, the geometric center of the device and associatedparts thereof. Said terminology will include the words abovespecifically mentioned, derivatives thereof and words of similar import.

Referring to FIGS. 1 and 2, there is shown an exploded perspective viewand an exploded edge view of a reusable airflow sensor especiallydesigned for use with a polysomnograph in a sleep lab setting. Thesensor comprises as its active element a polarized PVDF film layer 10that, in the embodiment of FIG. 1, is somewhat Y-shaped having roundedlobes 12, 14, diverging from one another at a predetermined angle and astem portion 16. The PVDF film layer 10 includes metallization layers onopposed major surfaces thereof represented by the cross-hatchingthereon. The metallization layers serve to collect the charge producedby the PVDF film due to respiratory air flow impinging on the transduceror due to temperature change.

Affixed to the opposed major surfaces of the stem portion 16 areconductive electrode tabs 18 and 20 that are crimped and/or soldered tothe exposed ends of insulated lead wires 22 and 24, respectively. Toinsure intimate contact between the conductive electrodes 18 and 20 andthe metalized surfaces of the PVFD film 10, a conductive adhesive, suchas that sold under the trademark ARclad® by Adhesives Research, Inc., isused. This material comprises an adhesive that is laced with conductivecarbon particles that serves as a bonding agent between the electrodes18 and 20 with the metalized layers adhered to the PVDF film. TheARclad® adhesive is represented in FIG. 1 by references numerals 26 and28.

Pyro/piezo transducers of the type described can be procured fromMeasurement Specialties, Inc. of Morristown, Pa., with leads alreadyattached to the metalized PVDF film, but the film shape is of onetype—rectangular—and of a standard size.

First and second double-sided adhesive tape layers 30 and 32 cut toconform to the shape of the PVDF layer 10 are adhered to the opposedsurfaces of the film layer 10 helping to secure the tab electrodes 18and 20 and a portion of the wire leads 22 and 24 leading to theconductive tabs in place. Completing the assembly are first and secondlayers 34 and 36 of polyurethane film that are also cut to be ofgenerally the same shape as the PVDF layer 10, but larger in size thanthe adhesive tape layers 30 and 32. During assembly, the polyurethaneplastic layer 34 is adhered to the exposed adhesive surface of thedouble-sided tape layer 30. Likewise, the polyurethane plastic layer 36is bonded to the exposed adhesive on the tape layer 32.

Because the polyurethane plastic layers 34 and 36 are of a larger areathan the tape layers 30 and 32, a perimeter portion 38 extends beyondthe edges of the tape layers 30 and 32. The perimeter portions of thepolyurethane layers 34 and 36 are brought into contact with one anotherand fused together in a thermal bonding process. As a result, theinterior components sandwiched between the outer polyurethane plasticlayers 34 and 36 are fully encapsulated and thereby sealed againstingress of moisture even when exposed to cleaning solutions andsterilants. Also, because of the manner in which the electrode tabs 18and 20 are adhered to the PVDF layer 10 by the ARclad® conductiveadhesive and the way in which the portion of the leads leading theretoare adhesively attached to the tape layers 30 and 32, testing has shownthat the wire leads 22 and 24 will break before the electrodes will pullfree from the sensor assembly.

While polyurethane film is preferred for the outer layers 34 and 36,because it is heat-sealable and hydrophobic, other non-porous heatsealable plastic materials may also be used to encapsulate the PVDF andthe distal ends of the lead wires.

In use, the sensor of FIG. 1 is placed on the upper lip of a subjectsuch that the lobes 12 and 14 are proximate the nasal openings and thestem portion 16 extends beyond the upper lip. Sensor 10 is held in placeon the lip by means of a suitable adhesive or by using a strip ofadhesive tape. Changes in temperature due to inspiratory and expiratoryairflow that impinges on the sensor produce an output signal componentproportional to the temperature swings. Should there be episodes ofsnoring, the sensor that is in contact with the skin, will sense thesnoring vibration and the piezoelectric properties of the PVDF willresult in a second signal component that varies with the intensity ofthe snoring. These signals are fed to a polysomnograph instrument wheresignal processing circuitry is used to separate the pyro signal from thepiezo signal.

Turning next to FIG. 3, there is shown an alternative embodimentespecially designed for attachment to the throat area of a sleepingpatient in a sleep lab environment. This sensor is also reusable in thatit can be cleaned. It is substantially identical in its construction tothe embodiment as illustrated in FIGS. 1 and 2 and correspondingnumbers, only primed, are applied to the embodiment of FIG. 3. The onlydifference between the embodiments of FIG. 1 and FIG. 3 is the shape ofthe sensor. In that the constructional details have already beenexplained in connection with the embodiment of FIGS. 1 and 2, it is feltunnecessary to repeat it in connection with the embodiment of FIG. 3.

This invention has been described herein in considerable detail in orderto comply with the patent statutes and to provide those skilled in theart with the information needed to apply the novel principles and toconstruct and use such specialized components as are required. However,it is to be understood that the invention can be carried out byspecifically different equipment and devices, and that variousmodifications, both as to the equipment and operating procedures, can beaccomplished without departing from the scope of the invention itself.

1-6. (canceled)
 7. A method of making a reusable snore/air flow sensorcomprising the steps of: (a) providing a film of material exhibitingpyroelectric and piezoelectric properties; (b) metalizing opposed majorsurfaces of said film; (c) cutting the metalized film of step (b) to adesired, predetermined shape configuration; (d) providing a pair of leadwires, each having a metal tab conductively secured to one end of saidwires; (e) affixing the metal tabs individually to opposite sides of themetalized film with a conductive adhesive; (f) overlaying the assemblyof step (e) on said opposite sides with a double-sided adhesive tape;(g) adhering a layer of moisture impervious, flexible plastic to thedouble-sided adhesive tape on each of the opposite sides of the assemblyof step (f) where the layers of plastic have the same shapeconfiguration as the metalized film; and (h) bonding perimeter portionsof the layers of flexible plastic one another to create a moistureimpervious seal.
 8. The method as in claim 7 wherein the perimeterportions are bonded in a thermal process.
 9. The method as in claim 7wherein the perimeter portions are bonded in a chemical process.
 10. Themethod as in claim 7 wherein the film is PVDF.
 11. The method as inclaim 10 wherein the predetermined shape configuration is generallyY-shaped.
 12. The method of claim 10 wherein the predetermined shapeconfiguration is generally rectangular, but with one rounded end.